Ammonia-hydrogen composite injection internal combustion engine based on ammonia online cracking separation and control method

Abstract

The invention discloses an ammonia-hydrogen composite injection internal combustion engine based on ammonia online cracking separation and a control method, and belongs to the technical field of internal combustion engines and clean energy power systems. The ammonia gas cracking branch and the ammonia fuel supply branch are connected in parallel between the liquid ammonia storage tank and the engine; the ammonia cracking branch comprises a first evaporator, a catalytic cracking reactor, a compressor, a hydrogen-nitrogen separation device, a hydrogen storage tank and a nitrogen storage tank, the hydrogen storage tank is connected with a cylinder of the engine through a hydrogen injection channel, and the nitrogen storage tank is connected with an intake manifold of the engine through a nitrogen injection channel; the ammonia fuel supply branch comprises a second evaporator and an ammonia gas storage tank, and the ammonia gas storage tank is connected with an air inlet manifold of the engine through an ammonia fuel injection channel. Liquid ammonia is adopted as fuel to prepare hydrogen through online cracking, hydrogen and nitrogen mixed gas is purified, the problem that the combustion efficiency is reduced by diluting the mixed gas with nitrogen can be avoided, and efficient and clean combustion is achieved through hydrogen, nitrogen and ammonia composite injection.

Description

Technical Field

[0001] This invention relates to the field of internal combustion engine and clean energy power system technology, and in particular to an ammonia-hydrogen composite injection internal combustion engine and control method based on online ammonia cracking and separation. Background Technology

[0002] With the global energy crisis and environmental pollution becoming increasingly severe, the development of efficient, low-carbon clean power systems has become an urgent need. Hydrogen energy, due to its high energy density and zero-carbon emissions, is considered an ideal clean energy source, but its practical application faces bottlenecks such as poor storage and transportation security and high infrastructure costs. Ammonia (NH3), as a hydrogen-rich (containing approximately 17.6% hydrogen), carbon-free fuel that is easily liquefied and stored, can serve as a hydrogen energy carrier and a zero-carbon fuel, showing significant application potential in shipping, power generation, and heavy transportation.

[0003] However, the widespread use of ammonia fuel is limited by its inherent combustion characteristics: firstly, ammonia has a high ignition temperature, making ignition difficult and its flame propagation speed slow, resulting in poor combustion stability and low efficiency in engines; secondly, pure ammonia combustion may produce nitrogen oxides (NOx) pollution, increasing the burden on exhaust gas treatment. To improve the combustion performance of ammonia, existing technologies typically employ a mixture of ammonia and hydrogen for combustion, utilizing the high reactivity of hydrogen to promote the ignition and combustion of ammonia. However, the current supply of hydrogen mainly relies on two methods: one is external refueling with high-pressure hydrogen or liquid hydrogen, but the construction cost of refueling facilities is high, and the safety requirements are stringent, making large-scale promotion difficult and lacking in economic efficiency and universality; the other is real-time hydrogen production through on-board ammonia cracking devices, which involves catalytically cracking ammonia into a hydrogen-nitrogen mixture (H2 / N2) and directly introducing it into the combustion chamber. Although this reduces construction costs, the hydrogen-nitrogen mixture produced by on-board ammonia cracking is not purified, and the nitrogen (which typically contains about 25% nitrogen in the mixture) will dilute the mixture, reducing combustion efficiency and thermal efficiency. Summary of the Invention

[0004] The purpose of this invention is to solve the above-mentioned technical problems and provide an ammonia-hydrogen composite injection internal combustion engine and control method based on online ammonia cracking and separation. Liquid ammonia is used as fuel, hydrogen is produced by online cracking, and the hydrogen-nitrogen mixture is purified to avoid the problem of nitrogen diluting the mixture and reducing combustion efficiency and thermal efficiency. High-efficiency and clean combustion is achieved through hydrogen, nitrogen and ammonia composite injection.

[0005] To achieve the above objectives, the present invention provides the following solution: The present invention discloses an ammonia-hydrogen composite injection internal combustion engine based on online ammonia cracking and separation, comprising a fuel supply system and an engine (31). The fuel supply system comprises a liquid ammonia storage tank (1), an ammonia cracking branch, and an ammonia fuel supply branch. The ammonia cracking branch and the ammonia fuel supply branch are connected in parallel between the liquid ammonia storage tank (1) and the engine (31). The ammonia cracking branch comprises a first evaporator (4), a catalytic cracking reactor (8), a compressor (12), and a hydrogen-nitrogen separation device (13) arranged sequentially along the flow direction. The inlet of the first evaporator (4) is connected to the liquid ammonia storage tank (1). The outlet of the tank (1) is connected to a hydrogen storage tank (15) and a nitrogen storage tank (26), respectively. The outlet of the hydrogen storage tank (15) is connected to the cylinder of the engine (31) through a hydrogen injection channel. The outlet of the nitrogen storage tank (26) is connected to the intake manifold of the engine (31) through a nitrogen injection channel. The ammonia fuel supply branch includes a second evaporator (19) and an ammonia storage tank (21) arranged sequentially along the flow direction. The inlet of the second evaporator (19) is connected to the outlet of the hydrogen-nitrogen separation device (13). The ammonia storage tank (21) is connected to the intake manifold of the engine (31) through an ammonia fuel injection channel.

[0006] Preferably, it also includes a cooling water circulation system, which includes a cooling water circulation loop, and the cooling water passages of the first evaporator (4), the second evaporator (19) and the engine (31) are connected in series through the cooling water circulation loop.

[0007] Preferably, the catalytic cracking reactor (8) is provided with an exhaust gas heat exchange sleeve (7) outside, and the air inlet of the exhaust gas heat exchange sleeve (7) is connected to the exhaust manifold of the engine (31).

[0008] Preferably, the system further includes a sensor control system, which includes a valve assembly module, a sensor module, and a control module; the valve assembly module includes a first pressure regulating valve (2), a first flow control valve (3), a second flow control valve (16), a second pressure regulating valve (17), a third flow control valve (18), a fourth flow control valve (22), an electronic throttle (23), a hydrogen fuel injection valve (24), a fifth flow control valve (27), a nitrogen injection valve (28), an ammonia fuel injection valve (29), and an exhaust gas three-way valve (30); the first pressure regulating valve (2) and the first flow control valve (3) are connected sequentially along the flow direction between the outlet of the liquid ammonia storage tank (1) and the first evaporator (4); the second flow control valve (16) is connected between the hydrogen storage tank (15) and the hydrogen fuel injection valve (24); the second pressure regulating valve (28) is connected between the hydrogen storage tank (15) and the hydrogen fuel injection valve (24); the second pressure regulating valve (29) is connected between the outlet of the liquid ammonia storage tank (1) and the first evaporator (4); the second flow control valve (29) is connected between the outlet of the liquid ammonia storage tank (1) and the first evaporator (4); the second pressure regulating valve (20) is connected between the outlet of the liquid ammonia storage tank (1) and the first evaporator (4); the second flow control ... 17) and the third flow control valve (18) are sequentially arranged between the outlet of the liquid ammonia storage tank (1) and the second evaporator (19) along the flow direction; the fourth flow control valve (22) is connected between the ammonia storage tank (21) and the ammonia fuel injection valve (29); the electronic throttle valve (23) is located before the intake manifold of the engine (31); the hydrogen fuel injection valve (24) is located in the hydrogen fuel injection channel; the fifth flow control valve (27) is connected between the nitrogen storage tank (26) and the nitrogen injection valve (28); the nitrogen injection valve (28) is installed on the intake manifold of the engine (31); the exhaust gas three-way valve (30) is located between the exhaust manifold of the engine (31) and the exhaust gas heat exchange sleeve (7); the ammonia fuel injection valve (29) is located in the ammonia fuel injection channel; The sensing module includes a first temperature sensor (6), a second temperature sensor (10), a speed sensor (32), a NOx sensor (33), a first pressure sensor (11), a second pressure sensor (14), a third pressure sensor (20), and a fourth pressure sensor (25); the first temperature sensor (6) is located in the cooling water circulation loop; the second temperature sensor (10) is located in the catalytic cracking reactor (8); the speed sensor (32) is located inside the engine (31); the NOx sensor (33) is located on the exhaust manifold of the engine (31) or before the aftertreatment device; the first pressure sensor (11) is located at the outlet of the catalytic cracking reactor (8); the second pressure sensor (14) is located on the hydrogen storage tank (15); the third pressure sensor (20) is located on the nitrogen storage tank (26); the third pressure sensor (20) is located on the ammonia storage tank (21); and the fourth pressure sensor (25) is located on the nitrogen storage tank (26). The control module includes an ECU (9), and both the valve group module and the sensing module are controlled by the ECU (9).

[0009] Preferably, the catalytic cracking reactor (8) is also integrated with an electric heater (5), which is electrically connected to the ECU (9), and the power of the electric heater (5) is supplied by a generator driven by the engine (31).

[0010] This invention discloses a control method for an ammonia-hydrogen composite injection internal combustion engine based on online ammonia cracking and separation, comprising the following steps: based on the real-time operating conditions of the engine (31), system pressure and temperature parameters, setting the intake opening of the intake manifold of the engine (31), and coordinating the control of the fuel ratio and injection sequence of the ammonia fuel injection channel, hydrogen injection channel and nitrogen injection channel, so as to realize flexible and coordinated control of ammonia, hydrogen and nitrogen, and optimize composite combustion and emissions.

[0011] Preferably, the monitoring signal from the second temperature sensor (10) is used by the ECU (9) to determine the thermal management status of the engine (31), and works in conjunction with the exhaust gas three-way valve (30) to ensure that the ammonia cracking and evaporation process is in the optimal temperature range.

[0012] Preferably, the hydrogen fuel injection valve (24) and the ammonia fuel injection valve (29) work independently to achieve ammonia-hydrogen composite injection; wherein, under normal load, hydrogen is used as an active fuel and mixed with ammonia in the cylinder; the nitrogen injection valve (28) injects nitrogen during the intake stroke of the engine (31) to ensure that nitrogen is fully mixed with air.

[0013] Preferably, the control logic of the sensor control system is as follows: T1 is set as coolant temperature, n is engine (31) speed, K is electronic throttle (23) opening, P actual is engine (31) actual power, P rated is engine (31) rated power, E hydrogen is hydrogen energy, E ammonia is ammonia energy, P hydrogen is hydrogen storage tank (15) pressure, Q nitrogen is nitrogen injection quantity, P nitrogen is nitrogen storage tank (26) pressure; Electronic throttle opening control: When T1 < 50℃ and n changes from n = 0 to n ≠ 0, it is determined to be a cold start mode, and 15% ≤ K ≤ 40% is controlled. The stored hydrogen in the hydrogen storage tank (15) is used as the fuel source until the ammonia cracking system stably produces hydrogen. When 50℃≤T1<80℃ and n idle speed -50rpm<n<n idle speed +50rpm, it is determined to be cold idle mode, and the control is 8%≤K≤20%; When T1≥80℃ and n_idle -50rpm<n<n_idle +50rpm, it is determined to be hot idle mode, and the control is 8%≤K≤20%; When T1 ≥ 80℃ and n (idle speed + 50 rpm) ≤ n ≤ 6000 rpm, it is determined to be normal load mode, and the control is 10% ≤ K ≤ 100%; When n≠0 becomes n=0, it is determined to be in shutdown mode, and control K=0; Ammonia-hydrogen combined injection energy ratio control: Under normal load mode, based on the ratio of the actual power P of the engine (31) to the rated power P, the ECU (9) calculates and controls the injection pulse width of the hydrogen fuel injection valve (24) and the ammonia fuel injection valve (29) respectively to achieve the ratio R of hydrogen energy to total fuel energy; where E hydrogen and E ammonia are the energy of hydrogen and ammonia respectively, calculated based on the mass flow rate of hydrogen and ammonia and their respective calorific values. The ECU (9) stores the calorific value data of hydrogen and ammonia, as well as the pulse width-flow characteristic curves of the hydrogen fuel injection valve (24) and the ammonia fuel injection valve (29) obtained through calibration. The ECU (9) determines the total fuel energy demand based on the power demand of the engine (31), and then calculates the hydrogen energy demand E_hydrogen target and the ammonia energy demand E_ammonia target based on the target R. Then, it converts the hydrogen mass flow rate demand W_hydrogen target and the ammonia mass flow rate demand W_ammonia target based on the calorific value. Finally, the ECU (9) obtains the corresponding hydrogen fuel injection valve (24) injection pulse width PWMH2 and the ammonia fuel injection valve (29) injection pulse width PWMNH3 by querying the pulse width-flow characteristic curves, and controls the operation of the injection valves. When Pactual ≤ Prated × 30% (low load), the hydrogen fuel injection valve (24) is open and the ammonia fuel injection valve (29) is closed, and hydrogen is supplied independently by the hydrogen storage tank (15), R = 100%; When P_rated × 30% < P_actual ≤ P_rated × 70%, both the hydrogen fuel injection valve (24) and the ammonia fuel injection valve (29) are opened, and the hydrogen storage tank (15) and the ammonia storage tank (21) provide energy together to control R to be maintained between 50% and 75%. When P_rated × 70% < P_actual ≤ P_rated, both the hydrogen fuel injection valve (24) and the ammonia fuel injection valve (29) are opened, and the hydrogen storage tank (15) and the ammonia storage tank (21) provide energy together to control R to be maintained between 25% and 50%. Ammonia cracking start-up and shutdown control: When Phydrogen ≤ 2.2 MPa or Pnitrogen ≤ 1.8 MPa, the ECU (9) starts the ammonia cracking system, including opening the first pressure regulating valve (2) and the first flow control valve (3) of the cracking branch, and activating the electric heater (5) of the catalytic cracking reactor (8). If the second temperature sensor (10) detects that the internal temperature of the catalytic cracking reactor (8) is lower than 400°C, the electric heater (5) is activated synchronously until the temperature reaches 450°C and then shuts down. When Phydrogen ≥ 2.8 MPa and Pnitrogen ≥ 2.2 MPa, the ECU (9) stops the ammonia cracking system, including closing the first pressure regulating valve (2) and the first flow control valve (3) of the cracking branch. Nitrogen injection control: Based on the engine load (31) and real-time NOx emission levels, the ECU (9) employs a feedforward-feedback composite control strategy to coordinate the opening and injection quantity of the nitrogen injection valve (28): Feedforward control base quantity: The ECU (9) obtains a base nitrogen injection quantity Q nitrogen base by looking up a table based on the pre-stored MAP diagram with engine (31) load rate (rated) and coolant temperature (T1) as input parameters, where the engine (31) load rate is P actual / P rated; Feedback closed-loop correction: The ECU (9) simultaneously receives the real-time nitrogen oxide concentration signal CNOx measured by the NOx sensor (33) and compares it with the target NOx concentration CNOx target stored in the ECU; and calculates a real-time correction coefficient KNOx through PID and other control algorithms. Final injection quantity decision: The final nitrogen injection command is determined by the feedforward base quantity and the feedback correction quantity. The final nitrogen injection quantity calculation formula is: Qnitrogen = Qnitrogen base × KNOx.

[0014] Preferably, the engine (31) P is determined by the ECU (9) in the following way: based on the engine (31) speed n detected by the speed sensor (32) and the engine (31) torque MAP stored in the ECU (9) based on the electronic throttle (23) opening and speed, it is obtained by the formula P_actual = k × n × M, where M is the engine (31) torque and k is the conversion coefficient, usually k = π / 30000, used to convert torque (N·m) and speed (rpm) into power units (kW).

[0015] The present invention achieves the following technical effects compared to the prior art: By using parallel ammonia cracking and ammonia fuel supply branches, a portion of liquid ammonia is catalytically cracked into a hydrogen-nitrogen mixture online. After purification by a separation unit, high-purity hydrogen and nitrogen are stored separately. Finally, through three independent injection channels for hydrogen, nitrogen, and ammonia, combustion and emission performance are optimized, achieving on-board online cracking. This solves the need for additional auxiliary fuel refueling, improves the combustion characteristics of ammonia by using hydrogen as an active fuel, effectively suppresses the formation of nitrogen oxides by using nitrogen injection, and significantly improves the power, economy, and environmental performance of the ammonia fuel engine through waste heat cascade utilization and optimized control under all operating conditions.

[0016] Other technical solutions of the present invention have achieved the following technical effects compared with the prior art: With the ECU as the core controller, the ECU is electrically connected to all sensors, various valves, and the electronic throttle. Based on the engine's real-time operating conditions and system pressure and temperature parameters, a coordinated control strategy is formulated. By precisely setting the injection timing and injection pulse width of each injection valve, the coordinated control of the electronic throttle opening and the fuel ratio and injection timing of the three fuel injection channels is achieved, enabling flexible and coordinated regulation of ammonia, hydrogen, and nitrogen, and optimizing compound combustion and emissions. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained by analyzing these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the structure of the ammonia-hydrogen combined injection internal combustion engine in an embodiment of the present invention; Figure 2 This is a schematic diagram of the structure of the ammonia-hydrogen combined injection internal combustion engine (including the control circuit of the ECU) in an embodiment of the present invention; Figure 3 This is a schematic flowchart of the control method for an ammonia-hydrogen combined injection internal combustion engine in an embodiment of the present invention.

[0019] Explanation of reference numerals in the attached drawings: 1. Liquid ammonia storage tank; 2. First pressure regulating valve; 3. First flow control valve; 4. First evaporator; 5. Electric heater; 6. First temperature sensor; 7. Exhaust gas heat exchange sleeve; 8. Catalytic cracking reactor; 9. ECU; 10. Second temperature sensor; 11. First pressure sensor; 12. Compressor; 13. Hydrogen-nitrogen separation device; 14. Second pressure sensor; 15. Hydrogen storage tank; 16. Second flow control valve; 17. Second pressure regulating valve; 18. Third flow control valve; 19. Second evaporator; 20. Third pressure sensor; 21. Ammonia storage tank; 22. Fourth flow control valve; 23. Electronic throttle; 24. Hydrogen fuel injection valve; 25. Fourth pressure sensor; 26. Nitrogen storage tank; 27. Fifth flow control valve; 28. Nitrogen injection valve; 29. ​​Ammonia fuel injection valve; 30. Exhaust gas three-way valve; 31. Engine; 32. Speed ​​sensor; 33. NOx sensor. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments analyzed and obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] The purpose of this invention is to provide an ammonia-hydrogen composite injection internal combustion engine and its control method based on online ammonia cracking and separation, in order to solve the problems existing in the prior art. Through parallel ammonia cracking and ammonia fuel supply branches, utilizing waste heat from engine exhaust, coolant, and electric heating, a portion of liquid ammonia is catalytically cracked online into a hydrogen-nitrogen mixture. After purification by a separation device, high-purity hydrogen and nitrogen are stored separately. Finally, an electronic control unit coordinates the control of three independent injection channels for hydrogen, nitrogen, and ammonia to optimize combustion and emission performance. This achieves on-board online cracking, solves the need for additional auxiliary fuel refueling, improves the combustion characteristics of ammonia by using hydrogen as an active fuel, effectively suppresses the formation of nitrogen oxides by using nitrogen injection, and significantly improves the power, economy, and environmental performance of the ammonia fuel engine through waste heat utilization and optimized control under all operating conditions.

[0022] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0023] Example 1 like Figures 1 to 3As shown, this embodiment provides an ammonia-hydrogen combined injection internal combustion engine based on online ammonia cracking and separation, including a fuel supply system and an engine 31. The fuel supply system includes a liquid ammonia storage tank 1, an ammonia cracking branch, and an ammonia fuel supply branch. The ammonia cracking branch and the ammonia fuel supply branch are connected in parallel between the liquid ammonia storage tank 1 and the engine 31.

[0024] The ammonia cracking branch includes a first evaporator 4, a catalytic cracking reactor 8, a compressor 12, and a hydrogen-nitrogen separation device 13 arranged sequentially along the flow direction. The inlet of the first evaporator 4 is connected to the outlet of the liquid ammonia storage tank 1, and the outlets of the hydrogen-nitrogen separation device 13 are respectively connected to a hydrogen storage tank 15 and a nitrogen storage tank 26. The outlet of the hydrogen storage tank 15 is connected to the cylinder of the engine 31 through a hydrogen injection channel, and the outlet of the nitrogen storage tank 26 is connected to the intake manifold of the engine 31 through a nitrogen injection channel.

[0025] The ammonia fuel supply branch includes a second evaporator 19 and an ammonia storage tank 21 arranged sequentially along the flow direction. The inlet of the second evaporator 19 is connected to the outlet of the hydrogen-nitrogen separation device 13, and the ammonia storage tank 21 is connected to the intake manifold of the engine 31 through the ammonia fuel injection channel.

[0026] Working principle: Liquid ammonia is stored in liquid ammonia storage tank 1. After flowing out of the outlet of liquid ammonia storage tank 1, the liquid ammonia splits into two streams: one flows into the ammonia cracking branch, and the other flows into the ammonia fuel supply branch. The liquid ammonia flowing into the ammonia cracking branch first enters the first evaporator 4 to evaporate and convert into room temperature ammonia gas. Then, the room temperature ammonia gas enters the catalytic cracking reactor 8, where, under the action of the catalyst and high temperature, the ammonia gas is decomposed into a hydrogen-nitrogen mixture. After being compressed by the compressor 12, it is sent to the hydrogen-nitrogen separation device 13 for separation, separating the mixture into high-purity hydrogen and nitrogen. The hydrogen gas enters the hydrogen storage tank 15 for temporary storage to provide an initial hydrogen reserve for the cold start of the engine 31 during initial system operation. The nitrogen gas enters the nitrogen storage tank 26 for temporary storage. The liquid ammonia flowing into the ammonia fuel supply branch enters the second evaporator 19 to evaporate and convert into room temperature ammonia gas. Then, the room temperature ammonia gas enters the ammonia storage tank 21 for temporary storage, serving as temporary storage and pressure stabilization for supplying ammonia fuel to the engine 31. Based on the real-time operating conditions of engine 31 and system pressure and temperature parameters, a coordinated control strategy is formulated. By setting the intake opening of the intake manifold of engine 31, the fuel ratio and injection timing of the ammonia fuel injection channel, hydrogen injection channel and nitrogen injection channel are coordinated to achieve flexible and coordinated regulation of ammonia, hydrogen and nitrogen, and optimize compound combustion and emissions.

[0027] This ammonia-hydrogen combined injection internal combustion engine uses liquid ammonia as fuel, produces hydrogen through online cracking, and purifies the hydrogen-nitrogen mixture to avoid the problem of nitrogen diluting the mixture and reducing combustion and thermal efficiency. It achieves efficient and clean combustion through hydrogen, nitrogen, and ammonia combined injection.

[0028] In one embodiment, a cooling water circulation system is also included. The cooling water circulation system includes a cooling water circulation loop. The cooling water passages of the first evaporator 4, the second evaporator 19, and the engine 31 are connected in series through the cooling water circulation loop. The heat from the cooling water of the engine 31 is used to provide a heat source for the evaporation of liquid ammonia in the first evaporator 4 and the second evaporator 19.

[0029] In one embodiment, the catalytic cracking reactor 8 is provided with an exhaust gas heat exchange sleeve 7. The air inlet of the exhaust gas heat exchange sleeve 7 is connected to the exhaust manifold of the engine 31, so as to use the waste heat of the engine 31 exhaust gas to provide a heat source for the cracking reaction.

[0030] In one embodiment, the system further includes a sensing control system, which includes a valve assembly module, a sensing module, and a control module. The valve assembly module includes a first pressure regulating valve 2, a first flow control valve 3, a second flow control valve 16, a second pressure regulating valve 17, a third flow control valve 18, a fourth flow control valve 22, an electronic throttle 23, a hydrogen fuel injection valve 24, a fifth flow control valve 27, a nitrogen injection valve 28, an ammonia fuel injection valve 29, and an exhaust gas three-way valve 30; the first pressure regulating valve 2 and the first flow control valve 3 are connected sequentially along the flow direction between the outlet of the liquid ammonia storage tank 1 and the first evaporator 4; the second flow control valve 16 is connected between the hydrogen storage tank 15 and the hydrogen fuel injection valve 24; the second pressure regulating valve 17 and the third flow control valve 18... 8 are sequentially arranged between the outlet of the liquid ammonia storage tank 1 and the second evaporator 19 along the flow direction; the fourth flow control valve 22 is connected between the ammonia storage tank 21 and the ammonia fuel injection valve 29; the electronic throttle valve 23 is located before the intake manifold of the engine 31; the hydrogen fuel injection valve 24 is provided with a hydrogen fuel injection channel; the fifth flow control valve 27 is connected between the nitrogen storage tank 26 and the nitrogen injection valve 28; the nitrogen injection valve 28 is installed on the intake manifold of the engine 31; the exhaust gas three-way valve 30 is located between the exhaust manifold of the engine 31 and the exhaust gas heat exchange sleeve 7; the ammonia fuel injection valve 29 is located on the ammonia fuel injection channel; The sensing module includes a first temperature sensor 6, a second temperature sensor 10, a speed sensor 32, a NOx sensor 33, a first pressure sensor 11, a second pressure sensor 14, and a third pressure sensor 20. The first temperature sensor 6 is installed in the cooling water circulation loop and is used to monitor the heat source temperature supplied to the first evaporator 4 and the second evaporator 19. The second temperature sensor 10 is installed in the catalytic cracking reactor 8 and is used to monitor the cracking temperature. The speed sensor 32 is installed inside the engine 31 to monitor the operating conditions of the engine 31; the NOx sensor 33 is installed on the exhaust manifold of the engine 31 or before the aftertreatment device to monitor the concentration of nitrogen oxides in the raw exhaust of the engine 31 in real time; the first pressure sensor 11 is installed at the outlet of the catalytic cracking reactor 8; the second pressure sensor 14 is installed on the hydrogen storage tank 15; the third pressure sensor 20 is installed on the nitrogen storage tank 26; the third pressure sensor 20 is installed on the ammonia storage tank 21; and the fourth pressure sensor 25 is installed on the nitrogen storage tank 26. The control module includes ECU9. Note: ECU stands for Electronic Control Unit, also known as "vehicle computer" or "on-board computer." ECU9 is the core controller, controlling both the valve assembly module and the sensor module. ECU9 is electrically connected to all sensors, various valves, and the electronic throttle valve 23. Based on the real-time operating conditions of the engine 31 and system pressure and temperature parameters, it formulates a coordinated control strategy. By precisely setting the injection timing and pulse width of each injection valve, it achieves coordinated control of the electronic throttle valve 23 opening and the fuel ratio and injection timing of the three fuel injection channels. This enables flexible and coordinated regulation of ammonia, hydrogen, and nitrogen, optimizing compound combustion and emissions.

[0031] In one embodiment, the monitoring signal of the second temperature sensor 10 is used by the ECU9 to determine the thermal management status of the engine 31, and works in conjunction with the exhaust gas three-way valve 30 to ensure that the ammonia cracking and evaporation process is in the optimal temperature range.

[0032] In one embodiment, the hydrogen fuel injection valve 24 and the ammonia fuel injection valve 29 operate independently to achieve ammonia-hydrogen composite injection; wherein, under normal load, hydrogen is used as an active fuel and mixed with ammonia in the cylinder.

[0033] In one embodiment, the ECU9 controls the nitrogen injection valve 28 to inject nitrogen during the intake stroke of the engine 31 to ensure that nitrogen is fully mixed with air.

[0034] In one embodiment, the catalytic cracking reactor 8 also integrates an electric heater 5, which is electrically connected to the ECU 9. The power for the electric heater 5 is supplied by a generator driven by the engine 31. The electric heater 5 is used to start during the cold start phase of the engine 31 or when the second temperature sensor 10 detects that the reactor temperature is below a set threshold, ensuring rapid start-up and stable operation of the ammonia cracking reaction.

[0035] In one embodiment, the hydrogen-nitrogen separation device 13 is a palladium alloy membrane separator or a molecular sieve pressure swing adsorption tower with a separation efficiency of not less than 95% to ensure that the hydrogen supplied to the engine 31 has sufficient purity.

[0036] In one embodiment, the nitrogen injection valve 28 is an intake manifold injection valve, which is installed on the intake manifold of the engine 31. It is mainly used to inject nitrogen into the intake airflow to dilute the intake oxygen concentration and reduce the temperature of the subsequent combustion process, thereby suppressing the formation of nitrogen oxides (NOx).

[0037] The catalytic cracking reactor 8 is filled with an ammonia cracking catalyst with ruthenium-based active components, and its optimal operating temperature range is 400℃~550℃.

[0038] In one embodiment, the exhaust gas three-way valve 30 is an electronically controlled three-way valve, whose default path is to allow the exhaust gas of engine 31 to flow through the exhaust gas heat exchange sleeve 7; when the second temperature sensor 10 detects that the internal temperature of the catalytic cracking reactor 8 exceeds the set upper limit, the ECU9 controls the exhaust gas three-way valve 30 to switch the path, so that the exhaust gas of engine 31 bypasses the exhaust gas heat exchange sleeve 7 and is directly discharged to the aftertreatment system to prevent the catalyst from overheating and failing.

[0039] In one embodiment, the working pressure range of the liquid ammonia storage tank 1 is 0.5 MPa to 2.0 MPa; the working pressure range of the hydrogen storage tank 15 and the nitrogen storage tank 26 is 2 MPa to 3 MPa.

[0040] In one embodiment, the cooling water temperature supplied by the cooling water circulation system to the first evaporator 4 and the second evaporator 19 is in the range of 80°C to 95°C.

[0041] In one implementation, a specific example is as follows: The liquid ammonia storage tank 1 is made of pressure-resistant steel, with a designed working pressure range of 0.8MPa to 1.5MPa and a volume of 100L. This volume can be adjusted according to the vehicle's driving range and the engine's power requirements. The first pressure regulating valve 2, model DR20G-1.5 / 40, stabilizes the pressure at 0.8MPa. The first flow control valve 3, model HSV-2020, has a maximum flow rate of 10L / min. The second pressure regulating valve 17, model DR20G-1.5 / 40, stabilizes the pressure at 0.8MPa. The third flow control valve 18, model HSV-2020, has a maximum flow rate of 15L / min.

[0042] The cooling water circulation system is connected to the cooling water passages of engine 31 (a modified four-cylinder diesel engine with a displacement of 2.0L), forming a closed-loop system. The cooling water circulation loop is connected in series with the shell side of the first evaporator 4 and the second evaporator 19 via metal pipes. Normal operation of engine 31 maintains the cooling water temperature within the range of 85℃ to 90℃, and this waste heat provides a stable heat source for liquid ammonia evaporation. A first temperature sensor 6 is installed on the pipeline from the engine 31's outlet water main to the evaporator section. The first temperature sensor 6 is an NTC thermistor with a range of -40℃ to 150℃, used to monitor the cooling water temperature supplied to the evaporator in real time. The outlet of the first flow control valve 3 is connected to the first evaporator 4 via a stainless steel pipe. The first evaporator 4 is a shell-and-tube heat exchanger with a heat exchange area of ​​0.5m². 2 The liquid ammonia is heated by the engine's cooling water in the engine 31 and completely vaporized into ammonia gas at approximately 25°C.

[0043] The catalytic cracking reactor 8 is a stainless steel cylindrical structure, internally filled with a ruthenium-based catalyst (Ru content 5wt%) supported on γ-Al₂O₃. The catalyst loading amount is designed based on the engine displacement 31 and the target hydrogen production rate, for example, 2.5L. The exhaust gas heat exchange sleeve 7's inlet is connected to the engine 31 exhaust gas passage via an electrically controlled three-way valve 30, used to switch the connection between the engine 31 exhaust gas passage and the engine 31 exhaust manifold. The engine 31 exhaust temperature is typically between 450℃ and 650℃, providing the main heat source for the exhaust gas heat exchange sleeve 7, thus maintaining the internal temperature of the catalytic cracking reactor 8 within the optimal operating range of 450℃ to 500℃. The electric heater 5 is an armored type, wound around the front end of the catalyst bed inside the catalytic cracking reactor 8. Its power is determined based on the cold start heating rate requirements, for example, 3kW-5kW.

[0044] The second evaporator 19 adopts a shell-and-tube heat exchanger, and its heat exchange area is designed according to the maximum ammonia fuel requirement of engine 31, for example, 0.8m². 2 The evaporated ammonia gas enters a 5L ammonia storage tank 21 at an operating pressure of 1.0MPa for temporary storage and pressure stabilization to ensure a stable supply to the engine 31. The compressor 12 is a piston compressor with a displacement and exhaust pressure of 2.5MPa, matched to the gas production rate of the catalytic cracking reactor 8 and the operating pressure of the hydrogen-nitrogen separation unit 13. The hydrogen-nitrogen separation unit 13 uses a palladium alloy membrane separator (Pd-23%Ag membrane), with the effective membrane area determined based on the peak hydrogen demand of the engine 31, for example, 0.8m². 2 At an operating pressure of 2.5 MPa, the hydrogen permeation purity is >99.5%, and the separation efficiency is >97%. Both the hydrogen storage tank 15 and the nitrogen storage tank 26 are designed to operate at pressures of 2 MPa to 3 MPa. The tank volumes can be adjusted according to the system's requirements for hydrogen storage and nitrogen pressure stabilization, and each is equipped with a safety valve.

[0045] The hydrogen injection channel, nitrogen injection channel, and nitrogen injection channel are three independently controlled injection channels directly connected to cylinder 31 of the engine. The hydrogen fuel injection valve 24 on the hydrogen injection channel is a high-pressure electromagnetic injection valve with a maximum withstand pressure of 15 MPa. The hydrogen fuel injection valve 24 is directly screwed into the pre-drilled hole in the cylinder head of engine 31 via a mounting bracket. The nitrogen injection valve 28 on the nitrogen injection channel is a low-pressure electromagnetic injection valve with a maximum withstand pressure of 1 MPa. This nitrogen injection valve 28 is fixed to the intake manifold of engine 31 via a mounting bracket, with its nozzle facing the direction of the intake airflow. The ammonia fuel injection valve 29 on the ammonia fuel injection channel is a low-pressure electromagnetic injection valve with a maximum withstand pressure of 1 MPa. This ammonia fuel injection valve 29 is fixed to the intake manifold of engine 31 via a mounting bracket, with its nozzle facing the direction of the intake airflow.

[0046] The ammonia-hydrogen combined injection internal combustion engine is based on a 32-bit high-performance automotive electronic control unit (ECU9), model Infineon TC297. Its hardware resources include multiple ADCs, PWM outputs, and a CAN bus interface. The second temperature sensor 10 is a type K thermocouple with a range of 0-800℃, inserted into the catalyst bed inside the catalytic cracking reactor 8. The speed sensor 32 is a magnetoelectric type, installed at the crankshaft end of the engine 31. The first pressure sensor 11 is a piezoresistive type with a range of 0MPa~4MPa, located at the outlet of the catalytic cracking reactor 8. The second pressure sensor 14 is a piezoresistive type with a range of 0MPa~5MPa, located on the hydrogen storage tank 15; the fourth pressure sensor 25 is a piezoresistive type with a range of 0MPa~5MPa, located on the nitrogen storage tank 26; and the third pressure sensor 20 is a piezoresistive type with a range of 0MPa~2MPa, located on the ammonia storage tank 21.

[0047] The ECU9 internally stores a 3D MAP and control algorithm calibrated based on extensive bench tests. After the system is powered on, the ECU9 continuously acquires all sensor signals and executes the following closed-loop control method based on the engine's real-time operating conditions and system status parameters: The control flow executed by ECU9 is defined as follows: T1 is the coolant temperature, n is the engine speed, K is the electronic throttle opening, P_actual is the actual power of engine, P_rated is the rated power of engine 31 (80kW), E_hydrogen is the hydrogen energy, E_ammonia is the ammonia energy, P_hydrogen is the pressure of hydrogen storage tank 15, Q_nitrogen is the nitrogen injection quantity, P_nitrogen is the pressure of nitrogen storage tank 26. ① Engine operating condition determination and electronic throttle control: When T1 < 50℃ and n changes from n = 0 to n ≠ 0, it is determined to be a cold start mode, and the control is 15% ≤ K ≤ 40%; When 50℃≤T1<80℃ and n is within the idle speed range of 800±50rpm, it is determined to be cold idle mode, and the control is 8%≤K≤20%; When T1≥80℃ and n is within the range of 800±50rpm, it is determined to be hot idle mode, and the control is 8%≤K≤20%; When T1≥80℃ and n is in the range of 850rpm to 4000rpm, it is determined to be the normal load mode, and K is linearly adjusted between 10% and 100% to meet the intake demand; When n≠0 becomes n=0, it is determined to be in shutdown mode, and control K=0.

[0048] ② The energy ratio of ammonia-hydrogen combined injection is controlled under normal load mode: The actual power (Pactual) is determined by ECU9 by querying the engine torque MAP calibrated based on the electronic throttle valve 23 opening and engine speed n, and using the formula Pactual = k × n × MM, where k is the obtained torque value in N·m. Based on the ratio of the engine 31's actual power (Pactual) to its rated power (Prated), ECU9 calculates and controls the injection pulse widths of the hydrogen fuel injection valve 24 and the ammonia fuel injection valve 29 according to the target energy ratio (R), to achieve the ratio of hydrogen energy to total fuel energy (RR = Ehydrogen / Ehydrogen + Eammonia). At low load, Pactual ≤ Prated × 30%: Hydrogen fuel injection valve 24 is open, ammonia fuel injection valve 29 is closed, and hydrogen is supplied independently by hydrogen storage tank 15, R = 100%; Under medium load conditions, Prated × 30% < Pactual ≤ Prated × 70%: both hydrogen fuel injection valve 24 and ammonia fuel injection valve 29 are open. ECU9, in conjunction with the second flow control valve 16 and the fourth flow control valve 22, maintains R between 60% and 70%.

[0049] Under heavy load conditions (70% × Prated < Pactual ≤ Prated): Both hydrogen fuel injection valve 24 and ammonia fuel injection valve 29 are open. ECU9 controls R to decrease to between 30% and 45%.

[0050] ③ Intelligent control of ammonia cracking start-up and shutdown and waste gas thermal management: Start-up and Heating: When Phydrogen ≤ 2.2 MPa or Pnitrogen ≤ 1.8 MPa, ECU9 starts the ammonia cracking system: opening the first pressure regulating valve 2 and the first flow control valve 3. Simultaneously, the exhaust gas three-way valve 30 is controlled to be in the default path, allowing the exhaust gas from engine 31 to flow through the exhaust gas heat exchange sleeve 7 to heat the cracking reaction. If the reading of the second temperature sensor 10 is below 400°C, the electric heater 5 is activated synchronously until the temperature reaches 450°C, after which it is shut off.

[0051] Stop: When Phydrogen ≥ 2.8 MPa and Pnitrogen ≥ 2.2 MPa, ECU9 stops the ammonia cracking system by closing the first pressure regulating valve 2 and the first flow control valve 3.

[0052] Over-temperature protection: When the second temperature sensor 10 detects that the temperature exceeds the set upper limit of 550°C, for example under heavy load conditions, the ECU9 immediately controls the exhaust gas three-way valve 30 to switch the passage, so that the high temperature exhaust gas bypasses the exhaust gas heat exchange sleeve 7 and is directly discharged to the after-treatment system, thereby cutting off the external heat source and preventing the catalyst from sintering and failing due to overheating.

[0053] ④ Nitrogen injection control: Based on engine load 31 and real-time NOx emission levels, ECU9 employs a feedforward-feedback composite control strategy to coordinate the opening and injection quantity of nitrogen injection valve 28: Feedforward control baseline quantity: Based on the pre-stored MAP diagram with engine load rate Pactual / Prated and coolant temperature T1 as input parameters, ECU9 obtains a baseline nitrogen injection quantity Qnitrogen baseline by looking up a table. This baseline quantity ensures rapid control response.

[0054] Feedback closed-loop correction: ECU9 simultaneously receives the real-time nitrogen oxide concentration signal (CNOx measured by NOx sensor 33) and compares it with the target NOx concentration (CNOx target) stored internally by the ECU. A real-time correction coefficient (KNOx) is calculated using control algorithms such as PID control.

[0055] Final injection quantity decision: The final nitrogen injection command is determined by the feedforward base quantity and the feedback correction quantity. The final nitrogen injection quantity calculation formula is: Qnitrogen = Qnitrogen base × KNOx.

[0056] The principle defined by this MAP chart is that Qni is positively correlated with both load rate and T. For example, Qni increases significantly under high temperature and high load conditions. ECU9 controls the nitrogen injection valve 28 to inject nitrogen during the intake stroke of engine 31, for example, within a window of 0° to 120° crankshaft angle after top dead center, to ensure that nitrogen is fully mixed with fresh air to form a homogeneous charge.

[0057] Example 2 like Figures 1 to 3 As shown, this embodiment provides a control method for an ammonia-hydrogen composite injection internal combustion engine based on online ammonia cracking and separation, used to control the ammonia-hydrogen composite injection internal combustion engine based on online ammonia cracking and separation in Embodiment 1, including the following steps: Based on the real-time operating conditions, system pressure, and temperature parameters of engine 31, the intake opening of the intake manifold of engine 31 is set, and the fuel ratio and injection timing of the ammonia fuel injection channel, hydrogen injection channel, and nitrogen injection channel are controlled in a coordinated manner to achieve flexible and coordinated regulation of ammonia, hydrogen, and nitrogen, thereby optimizing compound combustion and emissions.

[0058] Preferably, ECU9 is used as the core controller. Both the valve group module and the sensing module are controlled by ECU9. ECU9 is electrically connected to all sensors, various valves, and the electronic throttle valve 23. Based on the real-time operating conditions of the engine 31 and system pressure and temperature parameters, it formulates a coordinated control strategy. By precisely setting the injection timing and injection pulse width of each injection valve, it achieves coordinated control of the opening of the electronic throttle valve 23 and the fuel ratio and injection timing of the three fuel injection channels: ammonia fuel injection channel, hydrogen injection channel, and nitrogen injection channel. This enables flexible and coordinated regulation of ammonia, hydrogen, and nitrogen, optimizing compound combustion and emissions.

[0059] In one embodiment, the catalytic cracking reactor 8 is filled with an ammonia cracking catalyst with ruthenium-based active components, and the operating temperature range is 400°C to 550°C. The working pressure range of liquid ammonia storage tank 1 is 0.5MPa~2.0MPa; the working pressure range of hydrogen storage tank 15 and nitrogen storage tank 26 is 2MPa~3MPa. The cooling water circulation system supplies cooling water to the first evaporator 4 and the second evaporator 19 at a temperature range of 80℃ to 95℃.

[0060] In one embodiment, the monitoring signal from the second temperature sensor 10 is used by the ECU 9 to determine the thermal management status of the engine 31, and works in conjunction with the exhaust gas three-way valve 30 to ensure that the ammonia cracking and evaporation process is in the optimal temperature range.

[0061] In one embodiment, the hydrogen fuel injection valve 24 and the ammonia fuel injection valve 29 operate independently to achieve ammonia-hydrogen composite injection; wherein, under normal load, hydrogen is used as an active fuel and mixed with ammonia in the cylinder; the nitrogen injection valve 28 injects nitrogen during the intake stroke of the engine 31 to ensure that nitrogen is fully mixed with air.

[0062] In one embodiment, the control logic of the sensing control system is as follows: T1 is set as coolant temperature, n as engine speed, K as electronic throttle opening, P_actual as actual engine power, P_rated as rated engine power, E_hydrogen as hydrogen energy, E_ammonia as ammonia energy, P_hydrogen as hydrogen storage tank pressure, Q_nitrogen as nitrogen injection quantity, and P_nitrogen as nitrogen storage tank pressure. Electronic throttle opening control: When T1 < 50℃ and n changes from n = 0 to n ≠ 0, it is determined to be a cold start mode, and the control is 15% ≤ K ≤ 40%, and the reserve hydrogen in hydrogen storage tank 15 is used as the fuel source until the ammonia cracking system stably produces hydrogen. When 50℃≤T1<80℃ and n idle speed -50rpm<n<n idle speed +50rpm, it is determined to be cold idle mode, and the control is 8%≤K≤20%; When T1≥80℃ and n_idle -50rpm<n<n_idle +50rpm, it is determined to be hot idle mode, and the control is 8%≤K≤20%; When T1 ≥ 80℃ and n (idle speed + 50 rpm) ≤ n ≤ 6000 rpm, it is determined to be normal load mode, and the control is 10% ≤ K ≤ 100%; When n≠0 becomes n=0, it is determined to be in shutdown mode, and control K=0.

[0063] Ammonia-hydrogen combined injection energy ratio control: Under normal load mode, based on the ratio of the actual power P of engine 31 to the rated power P, ECU9 calculates and controls the injection pulse widths of hydrogen fuel injection valve 24 and ammonia fuel injection valve 29 according to the target energy ratio R = Ehydrogen / Ehydrogen + Eammonia, to achieve the proportion R of hydrogen energy to total fuel energy. Here, Ehydrogen and Eammonia are the energies of hydrogen and ammonia, respectively, calculated based on their mass flow rates and calorific values.

[0064] The ECU9 internally stores the calorific value data of hydrogen and ammonia, as well as the pulse width-flow characteristic curves of the hydrogen fuel injection valve 24 and the ammonia fuel injection valve 29 obtained through calibration. The ECU9 determines the total fuel energy demand based on the engine 31's power requirement, then calculates the hydrogen energy demand (Ehydrogen target) and the ammonia energy demand (Eammonia target) based on the target R, and then converts these values ​​into hydrogen mass flow rate demand (Whydrogen target) and ammonia mass flow rate demand (Wammonia target). Finally, the ECU9 obtains the corresponding injection pulse width (PWMH2) of the hydrogen fuel injection valve 24 and the injection pulse width (PWMNH3) of the ammonia fuel injection valve 29 by querying the pulse width-flow characteristic curves, and controls the operation of the injection valves.

[0065] When Pactual ≤ Prated × 30% of the small load, the hydrogen fuel injection valve 24 is open and the ammonia fuel injection valve 29 is closed, and hydrogen is supplied independently by the hydrogen storage tank 15, with R = 100%. When P_rated × 30% < P_actual ≤ P_rated × 70% under medium load, both hydrogen fuel injection valve 24 and ammonia fuel injection valve 29 are opened, and the hydrogen storage tank 15 and ammonia storage tank 21 jointly supply energy to control R to be maintained between 50% and 75%. When P_rated × 70% < P_actual ≤ P_rated maximum load, both hydrogen fuel injection valve 24 and ammonia fuel injection valve 29 are opened, and the hydrogen storage tank 15 and ammonia storage tank 21 jointly supply energy to control R to be maintained between 25% and 50%. Ammonia cracking start-up and shutdown control: When Phydrogen ≤ 2.2 MPa or Pnitrogen ≤ 1.8 MPa, ECU9 starts the ammonia cracking system, including opening the first pressure regulating valve 2 and the first flow control valve 3 of the cracking branch, and activating the electric heater 5 of the catalytic cracking reactor 8. If the second temperature sensor 10 detects that the internal temperature of the catalytic cracking reactor 8 is lower than 400°C, the electric heater 5 is activated synchronously until the temperature reaches 450°C and then shuts down. When Phydrogen ≥ 2.8 MPa and Pnitrogen ≥ 2.2 MPa, ECU9 stops the ammonia cracking system, including closing the first pressure regulating valve 2 and the first flow control valve 3 of the cracking branch. Nitrogen injection control: Based on engine load 31 and real-time NOx emission levels, ECU9 employs a feedforward-feedback composite control strategy to coordinate the opening and injection quantity of nitrogen injection valve 28: Feedforward control baseline quantity: Based on the pre-stored MAP diagram with engine load rate Pactual / Prated and coolant temperature T1 as input parameters, ECU9 obtains a baseline nitrogen injection quantity Qnitrogen baseline by looking up a table. This baseline quantity ensures rapid control response.

[0066] Feedback closed-loop correction: ECU9 simultaneously receives the real-time nitrogen oxide concentration signal (CNOx measured by NOx sensor 33) and compares it with the target NOx concentration (CNOx target) stored internally by the ECU. A real-time correction coefficient (KNOx) is calculated using control algorithms such as PID control.

[0067] Final injection quantity decision: The final nitrogen injection command is determined by the feedforward base quantity and the feedback correction quantity. The final nitrogen injection quantity calculation formula is: Qnitrogen = Qnitrogen base × KNOx.

[0068] In one embodiment, the engine 31P is actually determined by the ECU9 in the following way: based on the engine 31 speed n detected by the speed sensor 32 and the engine 31 torque MAP stored in the ECU9 based on the electronic throttle valve 23 opening and speed, it is obtained by the formula P_actual = k × n × M, where M is the engine 31 torque and k is a conversion coefficient, usually k = π / 30000, used to convert the torque N·m and speed rpm into the power unit kW.

[0069] The above results demonstrate that this invention effectively solves the problems of difficult ammonia fuel combustion, low efficiency, high NOx emissions, and catalyst thermal management by integrating online ammonia cracking, hydrogen-nitrogen separation, intelligent waste gas thermal management, and multi-fuel composite injection and intelligent control. At the same time, it overcomes the bottleneck of hydrogen storage and transportation, and realizes an efficient, clean, reliable, and self-sufficient ammonia fuel power system.

[0070] Specific examples have been used to illustrate the principles and implementation methods of this invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this invention. Furthermore, those skilled in the art will recognize that, based on the ideas of this invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of this invention.

Claims

1. An ammonia-hydrogen hybrid injection internal combustion engine based on ammonia online cracking separation, characterized in that, The application relates to a fuel supply system and an engine (31), wherein the fuel supply system comprises a liquid ammonia storage tank (1), an ammonia cracking branch and an ammonia fuel supply branch; the ammonia cracking branch and the ammonia fuel supply branch are connected in parallel between the liquid ammonia storage tank (1) and the engine (31); the ammonia cracking branch comprises a first evaporator (4), a catalytic cracking reactor (8), a compressor (12) and a hydrogen-nitrogen separation device (13) arranged in sequence along a flow direction; the inlet of the first evaporator (4) is connected with the outlet of the liquid ammonia storage tank (1); the outlet of the hydrogen-nitrogen separation device (13) is respectively connected with a hydrogen storage tank (15) and a nitrogen storage tank (26); the outlet of the hydrogen storage tank (15) is connected with a cylinder of the engine (31) through a hydrogen injection channel; the outlet of the nitrogen storage tank (26) is connected with an air intake manifold of the engine (31) through a nitrogen injection channel; the ammonia fuel supply branch comprises a second evaporator (19) and an ammonia storage tank (21) arranged in sequence along a flow direction; the inlet of the second evaporator (19) is connected with the outlet of the hydrogen-nitrogen separation device (13); the ammonia storage tank (21) is connected with the air intake manifold of the engine (31) through an ammonia fuel injection channel.

2. Ammonia-hydrogen combined injection internal combustion engine based on ammonia online cracking separation according to claim 1, characterized in that, A cooling water circulation system is further included, wherein the cooling water circulation system comprises a cooling water circulation loop, and the first evaporator (4), the second evaporator (19) and the cooling water channel of the engine (31) are connected in series through the cooling water circulation loop.

3. Ammonia-hydrogen combined injection internal combustion engine based on ammonia online cracking separation according to claim 2, characterized in that, The catalytic cracking reactor (8) is externally provided with a waste gas heat exchange sleeve (7), and the gas inlet of the waste gas heat exchange sleeve (7) is communicated with an exhaust manifold of the engine (31).

4. Ammonia-hydrogen combined injection internal combustion engine based on ammonia online cracking separation according to claim 3, characterized in that, The system further comprises a sensing control system, which comprises a valve group module, a sensing module and a control module; the valve group module comprises a first pressure regulating valve (2), a first flow control valve (3), a second flow control valve (16), a second pressure regulating valve (17), a third flow control valve (18), a fourth flow control valve (22), an electronic throttle valve (23), the hydrogen fuel injection valve (24), a fifth flow control valve (27), a nitrogen injection valve (28), an ammonia fuel injection valve (29) and a waste gas three-way valve (30); the first pressure regulating valve (2) and the first flow control valve (3) are sequentially connected between the outlet of the liquid ammonia storage tank (1) and a first evaporator (4) in the flow direction; the second flow control valve (16) is connected between the hydrogen storage tank (15) and the hydrogen fuel injection valve (24); the second pressure regulating valve (17) and the third flow control valve (18) are sequentially arranged between the outlet of the liquid ammonia storage tank (1) and a second evaporator (19) in the flow direction; the fourth flow control valve (22) is connected between the ammonia storage tank (21) and the ammonia fuel injection valve (29); the electronic throttle valve (23) is arranged in front of the intake manifold of the engine (31); the hydrogen fuel injection valve (24) is arranged in the hydrogen fuel injection channel; the fifth flow control valve (27) is connected between the nitrogen storage tank (26) and the nitrogen injection valve (28); the nitrogen injection valve (28) is installed on the intake manifold of the engine (31); the waste gas three-way valve (30) is arranged between the exhaust manifold of the engine (31) and the waste gas heat exchange sleeve (7); the ammonia fuel injection valve (29) is arranged in the ammonia fuel injection channel; The sensing module comprises a first temperature sensor (6), a second temperature sensor (10), a rotational speed sensor (32), a NOx sensor (33), a first pressure sensor (11), a second pressure sensor (14), a third pressure sensor (20) and a fourth pressure sensor (25); the first temperature sensor (6) is arranged in the cooling water circulation loop; the second temperature sensor (10) is arranged in the catalytic cracking reactor (8); the rotational speed sensor (32) is arranged inside the engine (31); the NOx sensor (33) is arranged on the exhaust manifold of the engine (31) or before the aftertreatment device; the first pressure sensor (11) is arranged at the outlet of the catalytic cracking reactor (8); the second pressure sensor (14) is arranged on the hydrogen storage tank (15); the third pressure sensor (20) is arranged on the nitrogen storage tank (26); the third pressure sensor (20) is arranged on the ammonia storage tank (21); the fourth pressure sensor (25) is arranged on the nitrogen storage tank (26); The control module comprises an ECU (9), and the valve group module and the sensing module are controlled by the ECU (9).

5. The ammonia-hydrogen hybrid injection internal combustion engine based on ammonia online cracking separation according to claim 4, characterized in that, The catalytic cracking reactor (8) is further integrated with an electric heater (5) which is electrically connected with the ECU (9), and the electric heater (5) is powered by a generator driven by the engine (31).

6. A control method for an ammonia-hydrogen combined injection internal combustion engine based on ammonia online cracking separation according to any one of claims 1 to 5, characterized by, The method comprises the following steps: Based on the real-time working condition of the engine (31), the system pressure and temperature parameters, the intake opening of the intake manifold of the engine (31) is set, and the fuel ratio and injection timing of the ammonia fuel injection channel, the hydrogen fuel injection channel and the nitrogen fuel injection channel are cooperatively controlled to realize flexible regulation and cooperation of ammonia, hydrogen and nitrogen, and to optimize the composite combustion and emission.

7. The control method according to claim 6, characterized by The monitoring signal of the second temperature sensor (10) is used for the ECU (9) to judge the thermal management state of the engine (31), and cooperates with the exhaust three-way valve (30) to jointly ensure that the ammonia cracking and evaporation process is in the best temperature range.

8. The control method according to claim 6, characterized by The hydrogen fuel injection valve (24) and the ammonia fuel injection valve (29) work independently to realize ammonia-hydrogen composite injection; wherein the hydrogen gas is mixed with the ammonia gas in the cylinder as active fuel under normal load; the nitrogen injection valve (28) sprays during the intake stroke of the engine (31) to make the nitrogen fully mixed with the air.

9. The control method according to claim 6, characterized by, The control logic of the sensing control system is as follows: T1 is the coolant temperature, n is the engine (31) speed, K is the electronic throttle opening, P actual is the actual engine (31) power, P rated is the rated engine (31) power, E hydrogen is the hydrogen energy, E ammonia is the ammonia energy, P hydrogen is the hydrogen storage tank (15) pressure, Q nitrogen is the nitrogen injection amount, and P nitrogen is the nitrogen storage tank (26) pressure; Electronic throttle opening control: When T1<50℃ and n changes from n=0 to n≠0, it is determined as a cold start mode, 15%≤K≤40% is controlled, and the reserved hydrogen in the hydrogen storage tank (15) is preferentially used as a fuel source until the ammonia cracking system stably produces hydrogen; When 50℃≤T1<80℃ and n idling-50rpm<n<n idling+50rpm, it is determined as a cold idling mode, 8%≤K≤20% is controlled; When T1≥80℃ and n idling-50rpm<n<n idling+50rpm, it is determined as a hot idling mode, 8%≤K≤20% is controlled; When T1≥80℃ and n idling+50rpm≤n≤6000rpm, it is determined as a normal load mode, 10%≤K≤100% is controlled; When n≠0 changes to n=0, it is determined as a stop mode, K=0 is controlled; Ammonia-hydrogen composite injection energy ratio control: In the normal load mode, based on the ratio of the actual engine (31) power P actual to the rated power P rated, the ECU (9) calculates and controls the injection pulse width of the hydrogen fuel injection valve (24) and the ammonia fuel injection valve (29) according to the target energy ratio R=E hydrogen / (E hydrogen+E ammonia) to realize the ratio R of the hydrogen energy to the total fuel energy; wherein E hydrogen and E ammonia are the energies of hydrogen and ammonia respectively, which are calculated based on the mass flow and the respective calorific values of hydrogen and ammonia. The ECU (9) stores the heat value data of hydrogen and ammonia, and the pulse width-flow characteristic curve of the hydrogen fuel injection valve (24) and the ammonia fuel injection valve (29) obtained through calibration; the ECU (9) determines the total fuel energy demand according to the engine (31) power demand, then calculates the hydrogen energy demand Ehydrogen target and the ammonia energy demand Eammonia target according to the target R, and converts them into the hydrogen mass flow demand Whydrogen target and the ammonia mass flow demand Wammonia target according to the heat value; finally, the ECU (9) obtains the corresponding hydrogen fuel injection valve (24) injection pulse width PWMH2 and the ammonia fuel injection valve (29) injection pulse width PWMNH3 by querying the pulse width-flow characteristic curve, and controls the injection valve to work; When Pactual≤P rated × 30% (small load), the hydrogen fuel injection valve (24) is opened, the ammonia fuel injection valve (29) is closed, hydrogen is independently supplied by the hydrogen storage tank (15), and R=100%; When P rated × 30%<Pactual≤P rated × 70%, the hydrogen fuel injection valve (24) and the ammonia fuel injection valve (29) are both opened, energy is supplied by the hydrogen storage tank (15) and the ammonia storage tank (21) together, and R is controlled to maintain between 50% and 75%; When P rated × 70%<Pactual≤P rated, the hydrogen fuel injection valve (24) and the ammonia fuel injection valve (29) are both opened, energy is supplied by the hydrogen storage tank (15) and the ammonia storage tank (21) together, and R is controlled to maintain between 25% and 50%; Ammonia cracking start-stop control: When Phydrogen≤2.2 MPa or Pnitrogen≤1.8 MPa, the ECU (9) starts the ammonia cracking system, including opening the first pressure regulating valve (2) and the first flow control valve (3) of the cracking branch, and activating the electric heater (5) of the catalytic cracking reactor (8), if the second temperature sensor (10) detects that the internal temperature of the catalytic cracking reactor (8) is lower than 400℃, the electric heater (5) is activated synchronously until the temperature reaches 450℃ and then closed; when Phydrogen≥2.8 MPa and Pnitrogen≥2.2 MPa, the ECU (9) stops the ammonia cracking system, including closing the first pressure regulating valve (2) and the first flow control valve (3) of the cracking branch; Nitrogen injection control: The ECU (9) uses a feedforward-feedback composite control strategy to cooperatively control the opening and injection amount of the nitrogen injection valve (28) based on the engine (31) load and the real-time NOx emission level: The feedforward control basis quantity: the ECU (9) obtains a basic nitrogen injection amount Qnitrogen basic by table lookup according to the pre-stored MAP diagram with engine (31) load rate and coolant temperature (T1) as input parameters, wherein the engine (31) load rate is Pactual / P rated ; Feedback closed-loop correction: the ECU (9) receives the real-time nitrogen oxide concentration signal CNOx measured by the NOx sensor (33) at the same time, and compares it with the target NOx concentration CNOx target stored in the ECU; through a PID control algorithm, a real-time correction coefficient KNOx is calculated; Final injection quantity decision: the final nitrogen injection instruction is determined by the feedforward basic quantity and the feedback correction quantity, and the final nitrogen injection quantity calculation formula is: QN2=QN2base×KNOx.

10. The control method according to claim 9, characterized by The engine (31)Pis actually determined by the ECU (9) in the following manner: based on the engine (31) rotation speed n detected by the rotation speed sensor (32) and the engine (31) torque MAP stored in the ECU (9) based on the electronic throttle valve (23) opening degree and the rotation speed, the engine (31)Pis obtained by the formula Pactual=k×n×M, wherein M is the engine (31) torque, k is a conversion coefficient, and k=π / 30000 is usually used to convert the torque (N·m) and the rotation speed (rpm) into power units (kW).

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